CONICET | Buscador de Institutos y Recursos Humanos

The increasing infestations of bed bugs and resistance to different classes of insecticides represent a new challenge to manage this pest. In particular, repellents are a good option to control populations when they begin to be resistant. In this study, we evaluated the repellence produced by synthetics chemicals on Cimex lectularius from laboratory and field-collected strains.The experiments were performed with the susceptible Harold Harlan strain, and four strains collected from different Argentinian localities and maintained in laboratory conditions. Previously, we identified pyrethroid and carbamates resistance in the field-collected strains. The arena was a circle filter paper divided in two zones with equal areas: an inner circle and an outer ring. A glass ring was placed on the paper to avoid bed bugs to scape. Technical grade chemicals used were N,N-Dietil-meta-toluamida (DEET), ethyl 3-[acetyl(butyl)amino]propanoate (IR3535) and δ-dodecalactone. Acetone was used as solvent. The outer zone of the arena was impregnated with 0.5 µl of repellent solution (1.40 mg/cm2). Arenas treated with acetone alone were used as controls. Five fifth instar nymphs were gently placed in the middle of the arena. The location of individuals was recorded visually each five minutes, during 1 hour. We calculated a Repellence Index for each strain and repellent: [(Nc?Nt)/Nc]x100, where Nc is the number of individuals in the outer zone in the control, and Nt is the number of individuals in the outer zone in the treated paper. Three replicates were carried out for each treatment.DEET and δ-dodecalactone were highly repellent to the Harold Harlan nymphs. However, IR3535 showed a low repellent effect to this strain. In all cases, resistant-strains showed significant lower repellency than the susceptible-strain. Differences in the effectiveness of these repellents and its possible relationship with detoxifying metabolism will be discussed.